The present invention relates to an axial flow fan assembly of the type that includes a substantially cylindrical housing, stator vanes positioned at the exit end of the housing, and a rotating fan positioned at the other end of the housing. One example of a prior art fan assembly of this type is described in Chou U.S. Pat. No. 5,215,438, the entirety of which is incorporated herein by reference. The fan assembly described in Chou is depicted in FIG. 7, and includes a housing 130 having a stator 120 positioned at the outlet end of the housing and a rotating fan 110 positioned at the inlet end of the housing. A motor 131 is supported by and suspended from the stator, and a shaft of the motor drives the fan.
The overall axial height of any fan assembly is an important design consideration, in that the axial height of the fan assembly is a major contributing factor to the overall axial height of the system in which the fan assembly is incorporated. In the prior art fan assembly depicted in FIG. 7, the overall axial height of the fan assembly tends to be relatively large, because the motor is supported almost entirely outside the fan assembly housing.
The distance between the fan blades and the vanes of the stator also is an important design consideration to avoid interaction between the two, which would otherwise increase fan noise. In the prior art fan assembly depicted in FIG. 7, the distance between the fan blades and stator vanes is less than one fan blade chord length, which causes increased fan noise.
It would be desirable to decrease the overall axial height of the fan assembly in order to allow use of the assembly in more compact systems (e.g., refrigeration systems for refrigerated vehicles). It also would be desirable to increase the axial distance between the fan blades and the stator vanes in order to reduce the amount of noise generated by the fan assembly.